Question

Na⁺ – K⁺ pump is found in membranes of many
cells, like nerve cells. It works against electro chemical
gradient and involve an integral protein ATPase.
For each molecule of ATP used
(a) 3 ions of Na⁺ are pumped out and two K⁺ are taken in.
(b) 3 ions of Na⁺ are taken in and 2K⁺ are pumped out.
(c) 2 ions of Na⁺ are thrown out and 3K⁺ are absorbed.
(d) 3 ions of K⁺ are absorbed and 3Na⁺ are pumped out.

Answer 1

Answer:

a

3 ions of Na⁺ are pumped out and two K⁺ are taken in.

Active Transport against Concentration Gradient

Answer 2

(a) 3 ions of Na⁺ are pumped out and two K⁺ are taken in.

Explanation:

Na⁺ – K⁺ pump is found in membranes of many  cells, like nerve cells which are excitable cells because their membrane are in a polarized state. Different types of ion channels which are selectively permeable to different ions are present on the neural membrane. When a neuron is not conducting any impulse, i.e. resting., the axonal membrane is relatively more permeable to potassium ions (K⁺) and nearly impermeable to sodium ions (Na⁺). Consequently, the exoplasm inside the axon contains high concentration of K⁺ and negatively charged proteins and low concentration of Na⁺. In contrast, the fluid outside the axon contains a low concentration of K⁺, a high concentration of Na⁺ and thus form a concentration gradient. These ionic gradients across the resting membrane are maintained by the active transport of ions by the Na⁺ – K⁺ pump which transport 3 ions of Na⁺ are pumped out and two K⁺ are taken into the cell.